Optical pick-up apparatus

ABSTRACT

An optical pick-up device adapted for irradiating light beams onto an optical disc to carry out recording or reproduction of information signals with respect to the optical disc. A movable portion in which coils for drive are provided at a lens holder of synthetic resin which holds an object lens is displaceably supported at a fixing portion including magnets opposite to the drive coils through suspensions doubling as electric current supply medium from an external circuit. At the lens holder, there are provided conductive portions formed by the resin plating method. End portions of the drive coils and one ends of the suspensions are soldered to the conductive portions, thus to carry out mechanical supporting with respect to the fixing portion of the movable portion and electric connection with respect to the external circuit of the drive coils.

This application is the national stage #371 of PCT/JP00/07084 dated Nov.12, 2000.

TECHNICAL FIELD

This invention relates to an optical pick-up device, and moreparticularly to an optical pick-up device used for irradiating lightbeams onto an optical disc caused to undergo rotational operation tocarry out recording of information signals onto the optical disc, or tocarry out reproduction of information signals recorded on the opticaldisc.

BACKGROUND ART

Hitherto, optical pick-up devices used for carrying out recording ofinformation signals with respect to an optical disc, or for reproducinginformation signals recorded on the optical disc includes an object lens(objective) for converging light beams emitted from light source toirradiate them onto signal recording surface of the optical disc, and isfurther provided with a movable portion for allowing the object lens toundergo drive displacement in a focusing direction in parallel to theoptical axis thereof and in a tracking direction of plane directionperpendicular to the optical axis, and a fixing portion for supportingthis movable portion. The movable portion includes drive coils, i.e.,focusing coil and tracking coil.

In this case, in order to allow the object lens to undergo drivedisplacement in the focusing direction and in the tracking direction sothat light beams focus on the signal recording surface of the opticaldisc to follow recording tracks, it is necessary to deliver, from theexternal, drive currents corresponding to focusing error signal andtracking error signal to the drive coils constituting the movableportion.

As the optical pick-up device adapted for delivering current from theoutside of the device to the drive coils of the movable portion, thereare optical pick-up devices as shown below.

An optical pick-up device 101 shown in FIGS. 1 and 2 comprises a movableportion 107 in which printed wiring boards for connection 106, 106 areattached at a lens holder 105 which has held an object lens 102, afocusing coil 103 and tracking coils 104, 104. This movable portion 107is supported so that it is permitted to undergo displacement in adirection in parallel to the optical axis of the object lens 102 and ina plane direction perpendicular to the optical axis through foursuspensions 110 having bottom end portions supported by a fixing portion108 and connected to a printed wiring board 109 for external connectionsupported at the fixing portion 108. By soldering front end portions ofthe four suspensions 110 which have displaceably supported the movableportion 107 and end portions of the focusing coil 103 and the trackingcoils 104 with respect to the printed wiring boards for connection 106,106, supporting with respect to the fixing portion 108 of the movableportion 107 and electrical conduction to the outside of the device ofthe respective coils 103, 104, 104 are realized.

Moreover, in an optical pick-up device 201 shown in FIGS. 3 and 4, thereare provided in a projected manner (hereinafter simply referred to asprojected as occasion may demand) plural coil binding projections 206 ata lens holder 205 which has held an object lens 202, a focusing coil 203and plural tracking coils 204 to constitute a movable portion 207 tobind end portions of the respective coils 203 and 204 with respect topredetermined coil binding projections 206 to solder thereat front endportions of four suspensions 210 having bottom end portions supported bya fixing portion 208 and connected to a printed wiring board 209 forexternal connection supported by the fixing portion 208 to realizesupporting with respect to the fixing portion 208 of the movable portion207 and electric conduction to the device outside of the respectivecoils 203, 204.

Meanwhile, in the optical pick-up device 101 shown in FIGS. 1 and 2, itis necessary to provide printed boards 106 for connection. As a result,the number of parts is increased. Further, space for providing theconnection printed boards 106 is required. Thus, not only weight of thedevice itself is increased, but also the device itself becomes largesized. Further, since the connection printed board 106 is attached atthe lens holder 105 by, e.g., adhesive agent, there results loweredresponsibility resulting from change with passage of time of adhesiveagent. In addition, there occurs increase in the number of assemblingsteps. This might also give the cause to increase production cost.

Further, the optical pick-up device 201 shown in FIGS. 3 and 4 requiresprojections like coil binding projections 206 at the lens holder 205.Thus, miniaturization is prevented as the result of the fact that suchprojections are provided. In addition, working for binding end portionsof the coils 203, 204 at the coil binding projections 206 is required.These results the increased number of assembling steps. This alsoconstitute the cause that the manufacturing cost is increased.

An object of this invention is to provide a novel optical pick-up devicewhich can solve the technical problems that the conventional opticalpick-up devices have.

Another object of this invention is to provide an optical pick-up devicewhich can reduce the number of parts, and realize light weight andminiaturization.

In the optical pick-up device according to this invention proposed inorder to attain such objects, a movable portion in which drive coil isprovided at a lens holder of synthetic resin for holding an object lensis supported at a fixing portion having magnet opposite to the drivecoil through suspensions doubling as electric current supply medium fromexternal circuit. Further, conductive portions formed by the resinplating method are provided at the lens holder to solder end portion ofthe drive coil and one ends of the suspensions to the conductiveportions to realize supporting with respect to the fixing portion of themovable portion and electric connection with respect to an externalcircuit of the drive coil.

In accordance with this optical pick-up device, the end portion of thedrive coil and one ends of suspensions are soldered to the conductiveportion integrally provided at the lens holder so that supporting withrespect to the fixing portion of the movable portion and electricconnection with respect to the external circuit of the drive coil arerealized. Accordingly, the number of parts is reduced andminiaturization of the device itself is realized. In addition, sincereduction in the number of parts is realized, the number of assemblingsteps is reduced. Thus, reduction in the manufacturing cost can berealized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view showing an example of aconventional optical pick-up device, and

FIG. 2 is an essential part enlarged perspective view thereof.

FIG. 3 is a schematic perspective view showing another example of aconventional optical pick-up device, and

FIG. 4 is an essential part enlarged perspective view thereof.

FIG. 5 is a schematic perspective view showing an example of an opticalpick-up device according to this invention, and

FIG. 6 is an essential part enlarged perspective view thereof.

FIG. 7 is a schematic perspective view showing another example of anoptical pick-up device according to this invention, and

FIG. 8 is an essential part enlarged perspective view thereof.

BEST MODE FOR CARRYING OUT THE INVENTION

An optical pick-up device according to this invention will now bedescribed with reference to the attached drawings.

The optical pick-up device 1 according to this invention comprises afixing portion 2 and a movable portion 3 as shown in FIG. 5.

The movable portion 3 is constituted by supporting an object lens 5 at alens holder 4 formed by synthetic resin to attach a focusing coil 6 andtracking coils 7, 7. At the lens holder 4, there is formed aframe-shaped coil holding portion 8 in a manner adjacent to the portionat which the object lens 5 is supported. At the inside of the coilholding portion 8, the focusing coil 6 is adhered (bonded). In addition,at the side surface of the side of the object lens 5 of the focusingcoil 6, there are adhered (bonded) the tracking coils 7, 7.

At four portions in total of upper and lower both surfaces correspondingto both side portions of the focusing coil 6 of the coil holding portion8, there are respectively formed conductive portions 9 formed by theresin plating method as shown in FIG. 6. The resin plating method whichforms these conductive portions 9 is a method of generally allowing theportion to be plated to be rough surface to precipitate conductive metalby the catalytic method at the portion caused to be rough surface.

Meanwhile, as an optical pick-up device used for compact optical discrecording/reproducing apparatus, there is used an extremely compactoptical pick-up device in correspondence with the recording/reproducingapparatus. The coil holding portion 8 constituting such compact opticalpick-up device 1 is also extremely compact, and the conductive portions9 provided at this coil holding portion 8 are formed at extremely verysmall portions. It is difficult to allow the extremely very smallportion of synthetic resin mold product to be rough surface to applycatalyzer thereto even if high level technology such as fine maskingtechnology, etc. is employed.

In view of the above, an approach is employed to form primary moldproduct by synthetic resin in which rough surface can be realized byacid or alkali liquid to allow the entire surface of this primary moldproduct to be rough surface to apply catalyzer such as palladiumchloride, etc. thereto. Further, the primary mold product is insertedinto the mold for secondary mold to implement secondary molding theretoso that only the portions in which conductive portions are formed areexposed to the surface to precipitate conductive metal by the chemicalplating method at the portion exposed to the surface and to whichcatalyzer is applied thereto, thus to conductive portions 9. Byemploying this approach, it is possible to form the conductive portions9 with good accuracy and at a low cost. In this case, even if there isconducted waste such that catalyzer is implemented onto the portionswhich do not serve as conductive portion 9, it is possible to form moreextremely inexpensively the conductive portions 9 as compared to thefact that difficult work such that fine masking is implemented to verysmall parts is carried out. In addition, since the entire surface of theprimary mold product is caused to be rough surface, the synthetic resinportion formed by the secondary molding is firmly tightly in contactwith the primary mold product so that physical strength is high.

It is to be noted that it is preferable that synthetic resin used in theprimary molding and synthetic resin used in the secondary molding havethe same coefficient of thermal expansion and have heat-resistance andhigh fluidity. As synthetic resion to satisfy such conditions, there is,e.g., liquid crystal polymer. However, such synthetic resin is notlimited to this liquid crystal polymer.

The fixing holder 2 includes a fixing portion holder 10. A printedwiring board 11 for external connection is fixed to the fixing portionholder 10, and circuit pattern formed at the external connection printedwiring board 11 is electrically connected to biaxial drive circuit byconnection member (not shown).

The bottom end portions of thin linear four suspensions 12 consisting ofmaterial having conductivity and spring elasticity are soldered torespective connection terminals of the external connection printedwiring board 11. Thus, supporting with respect to the fixing portion 2and electric connection with respect to circuits on the externalconnection printed wiring board 11 are realized.

End portions of respective coils 6, 7 are soldered to the predeterminedconductive portions 9. The relationship between end portions of thecoils 6, 7 and conductive portions 9 to which those end portions areconnected is determined in consideration of efficiency and performance.For example, one end of the focusing coil 6 is soldered to theconductive portion 9 of the upper side of one end portion, the other endof the focusing coil 6 is soldered to the conductive portion 9 of thelower side, one ends of the tracking coils 7, 7 are soldered to theconductive portions 9 of the upper side of the other side portion, andthe other ends of the tracking coils 7, 7 are soldered to the conductiveportions 9 of the lower side, etc.

Further, the other end portions of the four suspensions 12 areindividually soldered to the respective conductive portions 9, wherebysupporting with respect to the fixing portion 2 by the suspensions 12 ofthe movable portion 3 and electric connection with respect to thebiaxial drive circuit through the suspensions 12 and the externalconnection printed wiling board 11 of the respective coils 6, 7 arerealized.

It is to be noted that soldering with respect to respective conductiveportions 9 of end portions of the respective coils 6, 7 and solderingwith respect to respective conductive portions 9 of the respectivesuspensions 12 may be carried out by single soldering, i.e.,co-soldering (common soldering).

In addition, while magnetic field producing magnets for supplyingmagnetic field to respective coils 6, 7 are provided at the fixingportion 2, illustration thereof is omitted in FIGS. 5 and 6.

FIGS. 7 and 8 show another example of the optical pick-up deviceaccording to this invention, and the optical pick-up device 13 shown inFIGS. 7 and 8 also comprises a fixing portion 14 and a movable portion15 similarly to the above-mentioned optical pick-up device 1.

The movable portion 15 is constituted by supporting an object lens 17 ata lens holder 16 formed by synthetic resin to attach a focusing coil 18and plural tracking coils 19, 19.

The lens holder 16 is formed to be substantially rectangular, whereinthe object lens 17 is supported at the central portion thereof. On theouter circumference of this lens holder 16, the focussing coil 18 isprovided in such a manner that it is wound. At portions before and afterthis focussing coil 18, the tracking coils 19 are adhered (bonded).

Further, at four portions in total of upper and lower both surfaces ofboth side portions of the lens holder 16, conductive portions 20 formedby the resin plating method are respectively formed as shown in FIG. 8.

The fixing portion 14 includes a fixing portion holder 21, whereinbottom end portions of thin linear four suspensions 22 consisting ofmaterial having conductivity and spring elasticity are supported by thefixing portion holder 21, and are electrically connected to biaxialdrive circuit of the outside by connecting means (not shown).

End portions of the respective coils 18, 19 attached at the lens holder16 are respectively soldered to predetermined conductive portions 20.The relationship between end portions of coils 18, 19 and conductiveportions 20 to which they are soldered is determined in consideration ofefficiency and performance similarly to the above.

In addition, the other end portions of four suspensions 22 in whichbottom end portions are fixed to the fixing portion holder 21 areindividually soldered to the respective conductive portions 20, wherebysupporting with respect to the fixing portion 14 by the suspensions 22of the movable portion 15 and electric connection with respect tobiaxial drive circuit through the suspensions 22 of the respective coils18, 19 are realized.

It is to be noted that soldering with respect to respective conductiveportions 20 of end portions of respective coils 18, 19 and solderingwith respect to respective conductive portions 20 of respectivesuspensions 22 may be carried out by single soldering, i.e.,co-soldering (common soldering).

In addition, at the fixing portions 14, as shown in FIG. 7, magnets 23,23 for producing magnetic field are disposed in a manner opposite toeach other.

In accordance with the above-described optical pick-up device 1, 13according to this invention, end portions of the drive coils 6, 7; 18,19 are soldered to the conductive portions 9, 20 formed by the resinplating method at the lens holders 4, 16, and the other end portions ofthe suspensions 12, 22 of which bottom portions are supported by thefixing portions 2, 14 are soldered to the conductive portions 9, 20,whereby mechanical supporting with respect to the fixing portions 2, 14of the movable portions 3, 15 and electric connection with respect toexternal circuit of the respective drive coils 6, 7; 18, 19 are carriedout at the same time. Accordingly, reduction in the number of parts isrealized. As a result, the number of assembling steps is decreased.Thus, reduction of manufacturing cost can be realized. Further,miniaturization and light weight of the device itself can be realized.In addition, since there is no necessity to use, e.g., adhesive agentwhich is remarkably deteriorated with age in regard to electricconnection of drive coils 6, 7; 18, 19 and mechanical supporting withrespect to fixing portions 2, 14 of movable portions 3, 15, reliabilityis improved.

It should be noted that shapes and structures of respective portions ofthe above-mentioned respective embodiments all only illustraterespective examples of the embodiments at the time of carrying out thisinvention, and various modifications may be made within the scope wherethe gist of this invention is not altered.

INDUSTRIAL APPLICABILITY

In the optical pick-up device according to this invention, end portionsof the drive coils and one end portions of the suspensions are solderedto the conductive portions integrally provided at the lens holder,thereby making it possible to carry out, at the same time, mechanicalsupporting with respect to the fixing portion of the movable portion andelectric connection with respect to external circuit of drive coil.Accordingly, the number of parts is reduced. As a result, the number ofassembling steps is reduced, and reduction in the manufacturing cost canbe thus made. In addition, miniaturization and light weight of thedevice itself can be realized.

What is claimed is:
 1. An optical pick-up device including an objectlens and adapted for allowing the object lens to undergo drivedisplacement in a desired direction, wherein a movable portion in whicha drive coil is provided at a lens holder of synthetic resin which holdsthe object lens is supported at a fixing portion including a magnetopposite to the drive coil through suspensions doubling as an electriccurrent supply medium from an external circuit, wherein conductiveportions are formed on the lens holder and are fabricated fromprecipitate conductive metal to define a thin-film electricallyconductive surface area covering and adhering in direct facial contactto the lens holder, and wherein an end portion of the drive coil andrespective ends of the suspensions are soldered to the respectiveconductive portions to realize supporting with respect to the fixingportion and the movable portion and electric conduction with respect tothe external circuit.
 2. The optical pick-up device as set forth inclaim 1, wherein the movement directions of the object lens are twodirections, a first direction in parallel to an optical axis of theobject lens and a second direction perpendicular to the optical axis ofthe object lens, and the drive coil including a focusing coil and atracking coil.
 3. The optical pick-up device as set forth in claim 1,wherein the end portion of the drive coil and the respective endportions of the suspensions are fixed to the respective conductiveportions by solder.
 4. The optical pick-up device as set forth in claim1, wherein the conductive portions are formed by a resin plating method.5. An improved optical pick-up device including an optical pick-up bodyfabricated from a synthetic resin and having at least one rough surfaceportion, the improvement comprising: at least one conductive portionfabricated from precipitate conductive metal defining a thin-filmelectrically conductive surface area, the at least one conductiveportion covering and adhering in direct facial contact to the at leastone rough surface portion of the optical pick-up body.
 6. The improvedoptical pick-up device as set forth in claim 5, wherein the conductiveportions are formed by a resin plating method.